Authors\u2019 response on Perkins et al. (2021) \u201cDead in the water: comment on \u201cDevelopment of an aquatic exposure assessment model for imidacloprid in sewage treatment plant discharges arising from use of veterinary medicinal products\u201d

Beatrice Valles-Ebeling,Jackie Atkinson,Jan Achtenhagen,Michael Starp

doi:10.1186/s12302-021-00580-1

Beatrice Valles-Ebeling, Jackie Atkinson + Show 2 more

Open Access

https://doi.org/10.1186/s12302-021-00580-1

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Abstract

In 2020, Anthe et al. published a newly developed model to predict imidacloprid surface water concentrations stemming from sewage treatment plant (STP) effluent as a consequence of the use of veterinary medicinal products containing imidacloprid in the UK (Anthe in Environ Sci Eur (2020) 32:147, https://doi.org/10.1186/s12302-020–00424-4). The modelled data indicate that these veterinary medicinal products make only a very small contribution to the levels of Imidacloprid observed in the UK water monitoring programme.The commentary by Perkins et al. (Perkins in Environ Sci Eur (2021) 33:88, https://doi.org/10.1186/s12302-021-00533-8) questioned the validity and conclusions of the modelling approach. We believe the modelling approach, which considered what we anticipated to be, the major exposure pathways, gives a realistic picture of the chronic emission via STPs to UK rivers.

Highlights

Imidacloprid is an active ingredient included in plant protection, biocidal and veterinary medicinal products (VMPs)
The total amount applied per month is calculated from the month of highest frequency of use, which is August based on survey data, as a fraction of the annual amount of imidacloprid used in the sewage treatment plant (STP) catchment area
The fraction of imidacloprid released from treated pelt due to rain was set to 2% for collars and the input parameters Frain 0.02 is used in the scenario 3 “Walking dogs in rain” Based on the immersion tests with the collars and a safety factor > 10 taking into consideration the frequency of shampooing (Table S6 in Additional File 1), an average fraction Fwashing of 0.2 was calculated for the scenario 2 “Washing/bathing of dogs”

Summary

Background

Imidacloprid is an active ingredient included in plant protection, biocidal and veterinary medicinal products (VMPs). The total amount applied per month is calculated from the month of highest frequency of use, which is August based on survey data, as a fraction of the annual amount of imidacloprid used in the STP catchment area (see Eq 4 [1]). It is the daily average the model calculated to compare this with the chronic PNECs. There might be days with higher release and some with lower release, but it is reasonable to use the mean for comparison with the long-term chronic benchmark. The build of the model was the first time this has ever been done for veterinary medicines and it is not surprising that enhancements can be

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